JP3000973B2 - Digital communication system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a digital communication system of a hybrid system which collectively handles ATM data to be transmitted in an asynchronous transfer mode and STM data to be transmitted in a synchronous transfer mode. Data and ATM between many terminal stations connected to both ends of
The present invention relates to a digital communication system for performing multiplex transmission of data.

[0002]

2. Description of the Related Art Asynchronous transfer mode (ATM)
ATM premised on transfer in us Transfer Mode)
Synchronous transfer mode (STM: Synch
ronousTransfer Mode)
As a conventional technology of a hybrid digital communication that handles TM data, that is, a container, collectively,
A "digital communication system" disclosed in JP-A-3-258143 and a "terminal device" disclosed in JP-A-6-62002 are known.

[0003] In the former "digital communication system", first conversion means for exchanging cells, which are digital information in fixed-length packets, and exchanging containers, which are digital information accommodated in a high-speed channel having a fixed capacity. A digital communication system is assumed in which a communication node exchanges a frame including an overhead including a call control signal and a payload containing either a cell or a container via a switching unit having a second switching unit. . The communication node on the transmitting side includes first information form identification means for giving form information indicating whether the digital information to be transmitted is a cell or a container to the call control signal. The exchange means includes an identification / distribution means for providing the payload included in the frame to one of the first exchange means and the second exchange means in accordance with the morphological information relating to the incoming frame, and an overhead applied to the payload via the own means. And a second information type identification unit that matches the type information included in the payload with the type information included in the overhead given to the payload. The communication node on the receiving side
The information processing apparatus further includes third information type identification means for recognizing and displaying the type information related to the incoming frame.

[0004] According to the "digital communication system" having the above characteristics, a cell and a container which originally communicated via a transmission system and an exchange network having different attributes can be converted into the same call using a single digital transmission system. They can communicate simultaneously via control signals.

[0005] The latter "terminal apparatus" includes a first multiplexing / demultiplexing means for multiplexing and demultiplexing a plurality of containers, a second multiplexing / demultiplexing means for multiplexing and demultiplexing a plurality of cells, and the first multiplexing / demultiplexing means described above. Third multiplexing / demultiplexing means for multiplexing and demultiplexing the highway side signal of the multiplexing / demultiplexing means, and transmission line terminating means for performing mutual conversion between the highway side signal and the transmission line signal of the third multiplexing / demultiplexing means. It is characterized by having.
According to the “terminal device” having such features, the ATM
Data, that is, cells, and STM data, that is, containers, can be handled by the same device, and can be allocated on the same transmission path. Therefore, it is not necessary to provide node equipment and transmission lines corresponding to each of the ATM and the STM, and it is possible to reduce the cost required for installing the node equipment and improve the use efficiency of the transmission lines.

FIG. 8 shows, for reference, the overall configuration of a conventional digital communication system. The digital communication system to which the "terminal apparatus" described in Japanese Patent Laid-Open Publication No. 6-62002 is applied. 1 illustrates an example of a system.

The transmitting node 71 and the receiving node 72
They are connected via a transmission path 73. Sender node 71
Comprises one or more transmitting STM units 711 respectively connected to one or more transmitting STM subscriber terminals 74, one or more transmitting ATM units 712 respectively connected to one or more transmitting ATM subscriber terminals 75, One or more transmission-side STM termination units 713 connected to each transmission-side STM unit 711; one or more transmission-side ATM termination units 714 connected to each transmission-side ATM unit 712;
It has a path multiplexing unit 730 connected to all of the M terminating unit 713 and the transmitting-side ATM terminating unit 714. The receiving node 72 includes one or more receiving STM units 721 connected to one or more receiving STM subscriber terminals 76, respectively.
One or more receiving ATM units 722 connected to one or more receiving ATM subscriber terminals 77, one or more receiving STM termination units 723 connected to each receiving STM unit 721, One or more receiving-side ATM terminating units 724 connected to the receiving-side ATM unit 722, a receiving-side STM terminating unit 723, and a receiving-side ATM terminating unit 72.
4 and a path separation unit 731 that is connected to all four.

In this digital communication system, the transmitting side S
While transmitting data from the TM subscriber terminal 74 to the receiving STM subscriber terminal 76, the transmitting ATM subscriber terminal 7
The operation when data is transmitted from the H.5 to the receiving-side ATM subscriber terminal 77 will be described.

The STM data transmitted from the transmitting side STM subscriber terminal 74 is transmitted to the transmitting side STM in the transmitting side node 71.
The data is input to the unit 711. The transmission side STM unit 711 passes the input STM data to the transmission side STM termination unit 713. The transmission side STM termination section 713 is
All of the STM data passed from 1 are combined into a virtual container and sent to the path multiplexing unit 730. on the other hand,
The ATM data transmitted from the transmitting side ATM subscriber terminal 75 is input to the transmitting side ATM unit 712 in the transmitting side node 71. The transmitting-side ATM unit 712 passes the received ATM data to the transmitting-side ATM termination unit 714. Sender ATM
The termination unit 714 combines all of the ATM data passed from the transmission-side ATM unit 712 into a virtual container and sends the virtual container to the path multiplexing unit 730. The path multiplexing unit 730 includes a transmission-side STM termination unit 713 and a transmission-side ATM termination unit 71.
4 and multiplexes each virtual container sent from
DH (Synchronous Digital Hierarchy) section path data is generated, and the SDH section path data is output to the transmission path 73. The transmission path 73 includes a path multiplexing unit 73
The SDH section path data output from 0 is transmitted to the receiving node 72.

The path separating unit 731 in the receiving node 72
Receives the SDH section path data transmitted via the transmission line 73, restores each virtual container by performing the reverse of the multiplexing described above, and restores each virtual container to the corresponding destination STM termination on the receiving side. To the receiving side ATM termination unit 724. Each receiving side STM terminating unit 723 terminates the passed virtual container and
The TM data is restored, and the STM data is transmitted to the connected receiving-side STM unit 721. Each receiving ST
M section 721 outputs the STM data transmitted from receiving side STM termination section 723 to receiving side STM subscriber terminal 76. On the other hand, each receiving-side ATM termination unit 724 terminates the passed virtual container to restore the corresponding ATM data, and sends the ATM data to the connected receiving-side ATM unit 722. Each receiving-side ATM unit 722 outputs the ATM data sent from the receiving-side ATM termination unit 724 to the receiving-side ATM subscriber terminal 77.

FIG. 9 shows an example of SDH section path data transmitted via a conventional transmission line for reference. The SDH section path data 42 is
STM data path 42a and ATM data path 42b
Are multiplexed and overhead is added. Here, the STM data path 42a is made up of a virtual container in which each STM data is put together, and the ATM data path 42b is made up of a virtual container in which each ATM data is put together. Then, the STM data path 42a and the ATM
The multiplexing ratio of the data path 42b is assigned and set in advance for each virtual container path.

[0012]

In the digital communication system shown in FIG. 8, when changing the multiplexing ratio of the STM data and the ATM data, as described above, only the path of the combined virtual container is changed. You can only change the assignment settings. For this reason, if the transmission capacity allocated and set for each path does not match the actual data amount for each path, the available transmission capacity cannot be used effectively, resulting in a wasteful transmission capacity. Occurred.

This wasteful transmission capacity can be reduced to some extent by assigning a number of paths each having a smaller transmission capacity in advance. However, since the SDH section path data transmitted via each path includes an overhead, there is a problem that a useless transmission capacity is generated which is not used for transmitting data having meaning.

Further, each node previously holds path information including the transmission capacity of each path described above, and performs data transmission with another node based on this path information when performing data transmission with another node. Synchronous processing and protection processing are being performed. For this reason, when performing maintenance management of each node, there arises a problem that it is necessary to consider matching the contents of the path information held by the nodes connected to each other via a transmission line. did.

SUMMARY OF THE INVENTION An object of the present invention is to provide a digital communication system in which the generation of useless transmission capacity is suppressed, and the maintenance of each node concerning the transmission ratio between STM data and ATM data does not require consideration for matching with other nodes. A communication system is provided.

[0016]

According to the first aspect of the present invention, (a) the data amount given in the asynchronous communication mode is constant.
Cell storage to temporarily store ATM cells, which are the data of
Means and the ATM cells stored in the cell storage means.
Based on the transmission management information held, the transmission destination of this ATM cell
Destination mode determining means for determining the communication mode of the
Destination communication determined by destination mode determination means
ATM cells whose mode is synchronous communication mode are quasi-STM data.
Data to the first system and transmit
ATM cells whose communication mode is the asynchronous communication mode
Distributing means for distributing to the second system as positive ATM cells
And a plurality of primary STM data cells each of which is divided into STM frames which are data of indefinite data amount given in a frame unit corresponding to a time slot for each cycle in the synchronous communication mode , and each of which has the same data amount. And a positive S generated by the cell
Assigned to the first system by TM data cell and sorting means
The divided quasi-STM data cells are referred to as STM data cells.
And an STM data cell stored in the up-frame cell buffer and distributed by the distribution means to a second system.
A transmitting node having a multiplexing unit for multiplexing the obtained normal ATM cells into a single virtual container, and a transmitting unit for transmitting the virtual container to the transmission line in the asynchronous communication mode;
(B) A receiving unit that receives a virtual container from a transmission path in an asynchronous communication mode, and restores an STM data cell and a primary ATM cell from the virtual container , and distributes and outputs the STM data cell and the primary ATM cell to different systems. Restoration distribution unit and STM distributed and output from the restoration distribution unit
A down frame cell buffer for temporarily storing data cells and an STM data cell temporarily stored in the down frame cell buffer are combined to restore the corresponding STM frame. The digital communication system is provided with a receiving node having a framing unit for outputting the time slot corresponding to the time slot for each cycle.

[0017]

[0018]

[0019]

[0020]

[0021]

[0022]

[0023]

[0024]

[0025]

[0026]

That is, according to the first aspect of the present invention, on the transmitting node side, among the ATM cells provided in the asynchronous communication mode and having a constant data amount, the ATM cells whose transmission destination communication mode is the synchronous communication mode are: It is distributed to the first system as a quasi-STM data cell. In addition, ATM cells whose transmission destination communication mode is the asynchronous communication mode are distributed to the second system as primary ATM cells. A first STM data cell generated by dividing the STM frame, which is data having an indefinite data amount given in a frame unit corresponding to a time slot for each cycle in the synchronous communication mode, by a cell forming unit; Are stored in the up frame cell buffer as STM data cells. This ST
The M data cells are grouped together with the primary ATM cells into a single virtual container by the multiplexer. Then, the virtual container is transmitted to the transmission path in the asynchronous communication mode by the transmission unit. On the other hand, on the receiving node side, the virtual container transmitted via the transmission path is received by the receiving unit. Then, STM data cells and ATM cells are restored and distributed from the virtual container by the restoration and distribution unit. Among these, the STM data cells are combined by the framing unit, and the corresponding STM frame is restored. This STM frame includes a primary STM data cell and a quasi-STM data cell.

For this reason, S given in the synchronous communication mode
ATM frame and ATM given in asynchronous communication mode
It is not necessary to assign and set the transmission capacity to each cell in advance. And the STM data cell and A
The ratio with the TM cell can be set arbitrarily in cell units.
Therefore, the available transmission capacity can be effectively used, and the generation of useless transmission capacity can be suppressed to a minimum.

The control of the ratio between the STM data cells and the ATM cells can be realized only by adjusting the amount of STM data in the transmitting node, and it is necessary to consider matching with the receiving node. There is no.

Further, when an ATM cell given to a transmitting node in the asynchronous communication mode is to be received in the synchronous communication mode by the receiving node, the ATM cell is treated as an STM data cell in a pseudo manner. For this reason, processing is performed like data transmission in the synchronous communication mode even though transmission was performed in the asynchronous communication mode.

[0031] In a second aspect of the present invention, a single virtual container obtained by the multiplexing unit of the transmitting node in a digital communication system of claim 1, wherein comprises a plurality of STM data cells corresponding to at least one frame It is characterized by:

That is, in the second aspect of the present invention, a single virtual container transmitted at a time always includes a plurality of STM data cells corresponding to at least one frame. For this reason, the normal STM frame given in the synchronous communication mode and the communication mode of the transmission destination are the AT which is the synchronous communication mode.
The transmission delay amount of the M cell, that is, the quasi-STM data cell, can always be kept constant.

According to a third aspect of the present invention, in the digital communication system according to the first or second aspect , the multiplexing unit of the transmission node transmits the plurality of STM data cells stored in the up-frame cell buffer. Is used to generate a virtual container by giving priority to the primary ATM cells allocated to the second system.

That is, according to the third aspect of the present invention, even when ATM cells whose transmission destination communication mode is the asynchronous communication mode are concentrated at once, the STM data cell obtained by dividing the regular STM frame given in the synchronous communication mode and the transmission thereof are transmitted. The ATM cell in which the previous communication mode is the synchronous communication mode, that is, the quasi-STM data cell is preferentially used to generate a virtual container. For this reason, the occurrence of cell loss of the primary STM data cell and the quasi-STM data cell can be suppressed.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to embodiments.

FIG. 1 shows the overall configuration of a digital communication system according to a first embodiment of the present invention.

(Overall Configuration) The transmitting node 11 and the receiving node 12 are connected via a transmission line 13.
The transmitting node 11 is connected to one or more transmitting STM subscriber terminals 14 by one or more transmitting STM subscriber terminals 14.
Unit 111 and one or more sender ATM subscriber terminals 15
One or more transmitting-side ATM units 112 respectively connected to
And one or more transmission-side STM termination units 113 connected to each transmission-side STM unit 111, and one or more transmission-side ATM termination units 11 connected to each transmission-side ATM unit 112
4 and a cell multiplexing unit 115 connected to all of the transmission side STM termination unit 113 and the transmission side ATM termination unit 114. The receiving node 12 has one or more receiving STMs.
One or more receiving-side STM units 121 respectively connected to the subscriber terminals 16, one or more receiving-side ATM units 122 each connected to one or more receiving-side ATM subscriber terminals 17, and each receiving-side STM unit 121. One or more receiving STM terminations 123 to connect to and each receiving A
One or more receiving-side ATM terminating units 124 connected to the TM unit 122, the receiving-side STM terminating unit 123 and the receiving-side A
Cell separation unit 125 connected to all TM termination units 124
And

(Configuration of Transmitting Node: First Embodiment) FIG.
Shows the main parts of the transmitting node of the digital communication system of the present embodiment. The internal configuration of the transmitting STM terminating unit, the transmitting ATM terminating unit and the cell multiplexing unit in the transmitting node and their relationships are shown. Express.

The transmitting side STM terminating unit 113 transmits to the transmitting side ST
An up-frame termination unit 113a that performs termination processing of the STM data passed from the M unit 111 and generates an STM frame that is data of an undefined data amount corresponding to a time slot for each cycle in the synchronous communication mode.
The transmitting-side ATM terminating unit 114 performs terminating processing of the ATM data passed from the transmitting-side ATM unit 112 to generate an ATM cell as data having a constant data amount, and an up-sell terminating unit 114a. And an up-cell buffer 114b for temporarily storing the generated ATM cells. The cell multiplexing unit 115 divides the STM frame generated by the up-frame terminating unit 113a and outputs a plurality of STs each having the same data amount.
A cell unit 115a for generating M data cells, an up frame cell buffer 115b for temporarily storing the STM data cells generated by the cell unit 115a for one frame unit, and an STM data cell stored in the up frame cell buffer 115b After taking out a group of STM data cells preferentially, the ATM cells stored in the upsell buffer 114b are taken out, and these STM data cells and ATM cells are taken out.
A multiplexing unit 115c that multiplexes cells and outputs the multiplexed cells as a single virtual container, and SDH path data obtained by adding an overhead of an SDH path for specifying a destination path to the single virtual container output from the multiplexing unit 115c Produces
Output path overhead terminator 115d for outputting this
And an SDH section overhead for specifying a destination section is added to the SDH path data to add
An output section overhead terminator 115e for generating H section path data and outputting the generated data to the transmission line 13; Here, the output path overhead termination unit 115
d and output section overhead terminator 115e
Corresponds to a transmission unit that transmits a virtual container to a transmission path in the asynchronous communication mode.

(Configuration of Receiving Node: First Embodiment) FIG.
Shows the main parts of the receiving node of the digital communication system according to the present embodiment. The internal configuration of the receiving STM termination unit, the receiving ATM termination unit, and the cell separation unit in the receiving node and their relationships are shown. Express.

The cell separation unit 25 performs an SDH section termination process on the SDH section path data input from the transmission line 13 to generate SDH path data in which the SDH section overhead is removed, and an input section overhead termination unit 125a. An input path overhead terminator 125b that terminates the SDH path data input from the input section overhead terminator 125a to generate a single virtual container from which the SDH path overhead has been removed, and outputs the virtual container, and an input path overhead terminator A restoring and distributing unit 125c for terminating a single virtual container output from the unit 125b to restore STM data cells and ATM cells, and distributing and outputting the restored STM data cells and ATM cells to different systems; Restoration distribution unit 125c The outputted STM data cells 1
An STM frame is synthesized from a down frame cell buffer 125d that temporarily accumulates in units of a frame unit and STM data cells equivalent to one frame unit temporarily stored in the down frame cell buffer 125d, and the corresponding STM frame is obtained. And a framing unit 125e for restoring and outputting the STM frame in the synchronous communication mode in correspondence with a time slot for each cycle. Here, the input section overhead terminating unit 125a and the input path overhead terminating unit 125b correspond to a receiving unit that receives the virtual container from the transmission path in the asynchronous communication mode. The receiving-side STM termination unit 123 performs termination processing of the STM frame restored by the framing unit 125e to reproduce STM data, and transmits the STM data to the receiving-side STM unit 1
21 is provided with a down frame terminating unit 123a to be passed to the P.21. The receiving-side ATM termination unit 124 performs a termination process on the ATM cell output from the restoration distribution unit 125c to restore the ATM data, and temporarily stores the ATM data restored by the down-cell termination unit 124a. And a down cell buffer 124b.

(Structure of SDH Section Path Data) FIGS. 4 and 5 show an example of SDH section path data transmitted via the transmission line of the present embodiment. FIG. 5 shows the SDH section path data 40 occupied by the STM data cells of FIG.
SDH section path data 4 occupied by TM data cells 4
1 represents each.

(System Operation: First Embodiment) Next, in the digital communication system of the first embodiment, data is transmitted from the transmitting side STM subscriber terminal 14 to the receiving side STM subscriber terminal 16 and the transmitting side STM subscriber terminal 16 is transmitted. The operation when data is transmitted from the ATM subscriber terminal 15 to the receiving-side ATM subscriber terminal 17 will be described.

First, a path from the transmitting side STM subscriber terminal 14 to the receiving side STM subscriber terminal 16 via the transmitting side node 11 and the receiving side node 12 is set.
From the transmitting side ATM subscriber terminal 15 via the transmitting side node 11 and the receiving side node 12, the receiving side ATM subscriber terminal 1
7 is set.

(Operation of the transmitting side node: see FIG. 2) The STM data transmitted from the transmitting side STM subscriber terminal 14 is
The data is input to the transmission side STM unit 111 in the transmission side node 11. The transmitting side STM unit 111 transfers the input STM data to the transmitting side STM terminating unit 113 according to the set path information. The up-frame termination unit 113a in the transmission-side STM termination unit 113 performs termination processing of the STM data passed from the transmission-side STM unit 111 on a frame-by-frame basis, generates STM frames, and transmits the STM frames to the cell multiplexing unit 115 for each frame. I do. In the cell multiplexing section 115, the cell forming section 115a divides the STM frame sent from the up frame terminating section 113a to generate an STM data cell, and divides the STM data cell into an up frame cell buffer 115b.
To temporarily accumulate. The virtual path identifier on the STM data cell set by the cell unit 115a is set in advance for STM data, and is not used in an ATM cell described later.

On the other hand, the ATM data transmitted from the transmitting side ATM subscriber terminal 15 is input to the transmitting side ATM unit 112 in the transmitting side node 11. Transmission side ATM unit 112
Transfers the input ATM data to the transmission-side ATM termination unit 114 according to the set virtual path information. In the transmitting side ATM termination unit 114, the up-sell termination unit 114
a generates an ATM cell by terminating the ATM data passed from the transmitting-side ATM unit 112, and temporarily stores the ATM cell in the up-cell buffer 114b.

In cell multiplexing section 115, multiplexing section 1
15c, first, the up frame cell buffer 115b
The number corresponding to the difference between the number of ATM cells that can be transmitted in one frame and the number of previously extracted STM data cells after the STM data cells stored in the STM data cells are preferentially extracted for each frame of the virtual path. Is fetched from the up-cell buffer 114b, and these STM data cells and ATM cells are multiplexed and output to the output path overhead terminator 115d as a single virtual container. The output path overhead terminating unit 115d specifies the destination path to the single virtual container output from the multiplexing unit 115c according to the set path information S
It generates SDH path data to which the overhead of the DH path is added, and outputs this. The output section overhead terminator 115e further adds an SDH section overhead for specifying a destination section to the SDH path data to generate SDH section path data,
This is output to the transmission line 13.

(Relationship Between Operation of Receiving Node and SDH Section Path Data) In the SDH section path data 40 shown in FIG. 4, a group corresponding to the STM data transmitted from the transmitting STM section 111 to the cell forming section 115a. ST
The M data cells occupy the head of the payload, and the remaining transmittable number of ATM cells after subtracting the number of these STM data cells occupy the rear part of the payload.
On the other hand, the SDH section path data 41 shown in FIG.
Represents an example of data transmitted subsequent to the SDH section path data 40 described above. That is, SDH
In the section path data 41, the remaining ATM cells that could not be sent in the immediately preceding SDH section path data 40 are sent to the beginning of the payload from the transmission side STM unit 111 to the cell unit 1
A group of STMs corresponding to the STM data sent to 15a
The data cell is located in the center of the payload,
The remaining transmittable number of ATM cells after subtracting the number of M cells and the group of STM data cells occupy the rear part of the payload.

(Operation of the Receiving Node: See FIG. 3) In the cell separation unit 25, the input section overhead termination unit 125a performs termination processing of the SDH section on the SDH section path data input from the transmission line 13, and performs SDH section termination processing. SDH path data from which the section overhead has been removed is generated, and this is input to the input path overhead terminator 1.
25b. Input path overhead termination unit 125
b generates a single virtual container from which the input SDH path data is terminated by removing the SDH path overhead, and outputs this to the restoration distribution unit 125c. The restoration / distribution unit 125c includes an input path overhead termination unit 125
b) terminates the single virtual container output from b, restores the STM data cells and the ATM cells,
Data cells to the down frame cell buffer 125d,
The ATM cells are distributed to the receiving-side ATM termination unit 124 and output. Down frame cell buffer 125d
Temporarily stores the output STM data cells corresponding to one frame unit. The framing unit 125e restores the STM frame from the STM data cells corresponding to one frame unit temporarily stored in the down frame cell buffer 125d, and outputs this to the receiving side STM termination unit 123.

The down frame termination section 123a in the reception side STM termination section 123 performs termination processing of the STM frame restored by the framing section 125e, reproduces STM data, and transfers this to the reception side STM section 121. The receiving-side STM unit 121 sends the STM received from the down-frame termination unit 123a in accordance with the set path information.
The data is output to the corresponding receiving STM subscriber terminal 16.

On the other hand, the down-cell terminating unit 124a in the receiving-side ATM terminating unit 124 restores ATM data by terminating the ATM cell output from the restoring and distributing unit 125c, and outputs this to the down-cell buffer 124b. I do. The down-cell buffer 124b stores the restored ATM.
Temporarily store data. The receiving-side ATM unit 122 includes:
The ATM data stored in the down-cell buffer 124b is extracted and output to the corresponding receiving ATM subscriber terminal 17 in accordance with the set virtual path information.

(Effects of the First Embodiment: Basic Effects) According to the digital communication system of the first embodiment described above, the multiplexing unit 115c multiplexes the STM data cells and the ATM cells to form a single virtual container. In this case, the ratio between the STM data cells and the ATM cells can be arbitrarily set in cell units. Therefore, if the ratio between the STM data cells and the ATM cells is controlled so that the total amount of the STM data cells and the ATM cells to be transmitted does not exceed the preset transmission capacity, the available transmission is possible. Since the capacity can be used effectively and the generation of useless transmission capacity can be minimized, the overall transmission efficiency of the digital communication system can be improved.

Further, the control of the ratio of the STM data cells to the ATM cells can be realized only by adjusting the amount of the STM data in the transmitting side node 11, and
Since there is no need to consider matching with the receiving node 12,
Maintenance management relating to the transmission ratio between STM data and ATM data can be performed more reliably and easily than before.

Further, since the STM data cells are processed in units corresponding to one frame unit, the A
Despite processing as a TM cell, the transmission delay of STM data is maintained constant, and is equivalent to data transmission in the synchronous communication mode even though data transmission is actually performed in the asynchronous communication mode. In addition to the above-mentioned communication environment, the priority is given to processing of STM data cells, thereby suppressing the occurrence of data loss, which is a drawback of the generally known asynchronous transfer mode, and improving transmission quality at all times. Can be maintained.

(Second Embodiment) FIG. 6 shows a main part of a transmitting node of a digital communication system according to a second embodiment of the present invention. It shows the internal configuration of the ATM termination unit and the cell multiplexing unit and their relationship. In FIG. 6, FIG.
The same components as those described above are denoted by the same reference numerals.

The configuration of the transmitting node of the second embodiment is the same as that of the first node.
In the cell multiplexing unit 115 of the transmitting-side node according to the embodiment, the STM transmission capacity securing unit 115f is provided before the cell unit 115a.
Is added. This STM transmission capacity securing unit 115
f is the STM output from the transmission side STM termination unit 113.
ST for calculating the STM data amount which is the data amount of the frame
M data amount monitoring means, STM data amount determination means for determining a difference between the obtained STM data amount and a predetermined reference transmission amount, and the difference is determined in accordance with the difference determination result by the STM data amount determination means. And a reference transmission amount securing means for adding empty data having a data amount corresponding to the above to the STM frame.

(Effect peculiar to the second embodiment)
In the second embodiment provided with the TM transmission capacity securing unit 115f,
In particular, since the total amount of STM data cells included in the SDH section path data transmitted via the transmission line 13 is always maintained at a constant data amount, the total amount of ATM cells included in the SDH section path data is accordingly increased. Is also maintained at a constant data amount. For this reason, even when the state of data transmission in the synchronous transfer mode greatly fluctuates, fluctuations in the transmission amount of ATM cells in the asynchronous transfer mode are suppressed, and the stability of data transmission in the asynchronous transfer mode can be improved.

(Third Embodiment) FIG. 7 shows a main part of a transmission side node of a digital communication system according to a third embodiment of the present invention. It shows the internal configuration of the ATM termination unit and the cell multiplexing unit and their relationship. In FIG. 7, FIG.
The same components as those described above are denoted by the same reference numerals.

The configuration of the transmitting node according to the third embodiment is the same as that of the first embodiment.
In the transmission-side ATM termination unit 114 of the transmission-side node according to the embodiment, a distribution up-cell buffer 114c is provided instead of the up-cell buffer 114b. The distribution up-cell buffer 114c is connected to the up-cell termination unit 11
4a, a cell storage means for temporarily storing an ATM cell, which is data of a fixed data amount given in the asynchronous communication mode, based on transmission management information held by the ATM cell stored in the cell storage means. A destination mode determining means for determining a communication mode of a transmission destination of a cell, and a first system in which an ATM cell whose communication mode of the transmission destination determined by the destination mode determining means is a synchronous communication mode is defined as a quasi-STM data cell. And a distributing means for distributing the ATM cells in which the communication mode of the transmission destination is the asynchronous communication mode to the second system as primary ATM cells. For example, the transmission destination of the ATM cell is ST
For the M subscriber terminal 16, this ATM cell is a quasi-STM
The data cells are distributed to the first system, that is, the up frame cell buffer 115b, and output. Also, A
If the transmission destination of the TM cell is the ATM subscriber terminal 17 on the receiving side, the ATM cell is distributed to the second system, that is, the multiplexing unit 115c, as a primary ATM cell and output.

(Effect peculiar to the third embodiment) In the third embodiment in which the distribution up-cell buffer 114c is provided, in particular, the transmission-side ATM subscriber terminal 15 transmits the transmission-side node 11 and the reception-side node 12 When a virtual path to the receiving-side STM subscriber terminal 16 is set via the
The ATM data input from the TM subscriber terminal 15 is treated in a pseudo manner as the STM data cell described above. Therefore, data transmission in the asynchronous communication mode is processed like data transmission in the pseudo-synchronous communication mode, so that the transmission delay can be kept constant and data loss can be prevented.

[0061]

As described above, according to the first aspect of the present invention, the transmission capacity is previously assigned to the STM frame provided in the synchronous communication mode and the ATM cell provided in the asynchronous communication mode. There is no need, and the ratio between STM data cells and ATM cells can be set arbitrarily on a cell-by-cell basis, and the use of available transmission capacity can be effectively used to minimize the generation of useless transmission capacity. Therefore, the overall transmission efficiency of the digital communication system can be improved.

Further, the control of the ratio between the STM data cells and the ATM cells can be realized by adjusting the amount of STM data in the transmitting node, and there is no need to consider the matching with the receiving node. , The maintenance management relating to the transmission ratio between the STM data cells and the ATM cells can be performed reliably and easily.

[0063]

[0064]

[0065]

[0066]

[0067]

Further, when an ATM cell provided to a transmitting node in an asynchronous communication mode is to be received by a receiving node in a synchronous communication mode, the ATM cell is treated as an STM data cell in a pseudo manner, and Is processed like the data transmission by. Therefore, ATM
The communication environment of the cell can be the same as that of the data transmission in the synchronous communication mode.

According to the second aspect of the present invention, in the first aspect of the present invention, a single virtual container transmitted at a time always includes a plurality of STM data cells corresponding to at least one frame. Therefore, the transmission delay amount of the ATM cell in which the communication mode of the primary STM frame and the transmission destination provided in the synchronous communication mode is the synchronous communication mode, that is, the transmission delay amount of the quasi-STM data cell is always kept constant. ATM is a synchronous communication mode
Regarding the cell, although the data transmission is actually performed in the asynchronous communication mode, the communication environment can be the same as that of the data transmission in the synchronous communication mode.

[0070] According to the second aspect of the invention, in the invention of claim 1 or 2, wherein, even when the ATM cell communication mode of the transmission destination is the asynchronous communication mode is concentrated at a time, in the synchronous communication mode Since the STM data cell obtained by dividing the given primary STM frame and the ATM cell in which the communication mode of the transmission destination is the synchronous communication mode, that is, the quasi-STM data cell, are used preferentially, the virtual container is generated. The cell loss of the cell and the quasi-STM data cell can be suppressed, and the transmission quality of the ATM cell whose transmission mode is the synchronous communication mode and the STM frame given in the synchronous communication mode can always be kept good. .

[Brief description of the drawings]

FIG. 1 is a block diagram showing an overall configuration of a digital communication system according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a main part of a transmitting node of the digital communication system according to the embodiment.

FIG. 3 is a block diagram showing a main part in a receiving node of the digital communication system according to the embodiment.

FIG. 4 is a diagram illustrating an example of SDH section path data transmitted via a transmission line according to the embodiment;

FIG. 5 is a diagram illustrating an example of SDH section path data transmitted via a transmission line according to the embodiment;

FIG. 6 is a block diagram showing a main part of a transmitting node of a digital communication system according to a second embodiment of the present invention.

FIG. 7 is a block diagram showing a main part of a transmitting node of a digital communication system according to a third embodiment of the present invention.

FIG. 8 is a block diagram showing, for reference, the overall configuration of a conventional digital communication system.

FIG. 9 is a diagram showing, for reference, an example of SDH section path data transmitted via a conventional transmission path.

[Explanation of symbols]

11 Sending Node 12 Receiving Node 111 Sending STM Unit (STM: Synchronous Tra
nsfer Mode) 112 Sending side ATM unit (ATM: Asynchronous Tra)
nsfer Mode) 113 Transmission side STM termination section 113a Up frame termination section 114 Transmission side ATM termination section 114a Up cell termination section 114b Up cell buffer 114c Distribution up cell buffer 115 Cell multiplex section 115a Cell conversion section 115b Up frame cell buffer 115c Multiplex Decomposition unit 115f STM transmission capacity securing unit 121 Reception side STM unit 122 Reception side ATM unit 123 Reception side STM termination unit 124 Reception side ATM termination unit 124a Down cell termination unit 124b Down cell buffer 125 Cell separation unit 125c Restoration distribution unit 125d Down frame cell Buffer 125e framing unit

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-10-178451 (JP, A) JP-A-8-321818 (JP, A) JP-A-6-32002 (JP, A) JP-A-3-3 258143 (JP, A) US Patent 5,390,184 (US, A) IEICE Technical Report, SSE 96-170, p. 47-52 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/56

Claims (3)

(57) [Claims] 1. An amount of data given in an asynchronous communication mode
A cell that temporarily stores ATM cells that are constant data
Storage means and ATM cells stored in the cell storage means
Based on the transmission management information held by the ATM cell.
Destination mode determining means for determining the communication mode of the destination,
Of the destination determined by the destination mode determination means.
ATM cells whose communication mode is synchronous communication mode are quasi-ST
While sorting to the first system as M data cells,
AT in which the communication mode of the transmission destination is an asynchronous communication mode
A method for distributing M cells as primary ATM cells to the second system.
A minute unit, dividing the STM frame which is a data amount indeterminate data given in units of frames corresponding to the time slots of each cycle in the synchronous communication mode, a plurality of positive STM is any data of the same data amount Data set
A cell unit for generating Le, produced by the cell unit
The STM data cell and the distribution means
The quasi-STM data cells allocated to one system are STM
An up-frame cell buffer for temporarily storing data cells, an STM data cell stored in the up-frame cell buffer, and the
A multiplexing unit that multiplexes the primary ATM cells allocated to the two systems and combines them into a single virtual container, and a transmitting unit that transmits the virtual container to the transmission line in the asynchronous communication mode. node and a receiving section that receives a virtual container in the asynchronous communication mode from the transmission line, the restore from the virtual container STM data cells and the positive ATM cell, the distribution output these STM data cells and positive ATM cells to a different system, respectively and restoring distribution unit for a down frame cell buffer for temporarily storing STM data cells to be distribution output from the restoration distribution unit, the corresponding temporarily stored STM data cell to the down frame cell buffer synthesized and The STM frame to be used, and output this STM frame in the synchronous communication mode in correspondence with the time slot for each cycle. Digital communication system characterized by comprising a receiver node and a framing section for. 2. The digital communication system according to claim 1, wherein a single virtual container obtained by the multiplexing unit of the transmission node includes a plurality of STM data cells corresponding to at least one frame unit. 3. A multiplexing unit of the transmission node, comprising: a plurality of STMs stored in the up frame cell buffer;
The positive A , in which the data cell is allocated to the second system
3. The digital communication system according to claim 1, wherein the virtual container is generated by using the TM container with priority.